Lightning-arrester



(No Model.)

E. M. HEWLETT.

LIGHTNING ARRESTBR.

No. 587,818.. Patented Aug. 10, 1897.

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UNITED STATES PATENT OEETcE.

EDW'ARD M. HEVLETT, OF SOHENEOTADY, NET YORK, ASSIGNOR TO THE GENERALELEOTRlO COMPANY, OF NElV YORK.

LIGHTNING-ARRESTER.

SPECIFICATION forming part of Letters Patent No. 587,818, dated AugustK10, 1897.

Application led March 1G, 1897. Serial No. 627,824. (No model.)

To all whom t may concern.-

Be itknown that I, EDWARD M. HEWLETT, a citizen of the United States,residing at Schenectady, in the county of Schenectady,State of New York,have invented certain new and useful Improvements inLightning-Arresters, (Oase No. 545,) of which the following is aspecification.

The present invention relates to lightningarresters which are employedfor protecting electric apparatus from lightning discharges, and has forits object to provide a cheap, compact, and reliable arrester soarranged that the electrodes over which the lightning discharges passmay be readily inspected and removed.

In the accompanying drawings, attached to and made a part of thisspecification, Figure l is a plan view of the arrester with the coverremoved. Fig. 2 is a longitudinal section taken on the line 2 2 of Fig.l. Fig. 3 is a transverse section taken on the line 3 3 of Fig. l, andFig. 4 is a diagram of the circuit connections.

The inclosing box A is made of porcelain or other insulating materialand is preferably formed in one piece. Extending parallel with andadjacent to one side of the box are two graphite rods B, mounted in ametallic support C at one end and in a metal support E at the other end.The support O is electrically connected to the ground-terminal D. Thegraphite rods form a non-inductive resistance on the ground side of thearrester and prevent the dynamo-current following the lightningdischarge.

Secured to the bottom of the box by screws is a blow-out magnet F,having rectangular pole-pieces F F2, which are located on opposite sidesof the cover extension K' and the arcing electrodes G G. Located on thegraphite rods, between the supports O and E, is a clamp H, and to thesupport E and the clamp I-I are connected the terminals of the energiz-45 ing-coil I of the blow-out magnet. The coil I is provided with asuitable core and is insulated from the core and the pole-pieces by micaor other insulating material. The coil is energized when thedynamo-current follows 5o a lightning discharge to ground, and thecurrent therein depends upon the rela-tive resistances of the coil andthat portion of the graphite rods between the support E and the clamp H.

Extending diagonally along the base of the box is a metal strip J,connected at one end to support E and provided at the other end with acontact J', extending at right angles Ithereto and engaging with aspring-contact CZ, carried on the cover K. Mounted in line 6o with thecontact J' is a similar contact L in electrical connection with theline-terminal L. The contact L also engages with a contact on the coverK.

The cover K is preferably made of porcelain, and formed integraltherewith on its under side is an extension K. Binding-posts M aresecured in sockets in the ends of the extension by screws N. Eachbindingpost consists of a pair of arms c, adapted to clamp the 7o copperelectrodes G in position, and a pair of spring contact-arms d, adaptedto engage with the stationary contacts on the base ot the box. Theelectrodes G G are separated by a slight air-space over which thelightning passes to ground. Extending below the electrodes and on bothsides are projections 7o, which protect the pole-pieces F Fgfrom arcing.Aslightlytapered chute P carries oft the vapor formed between the arcingelectrodes and at the saine 8o time restrains the arc to a directiontransverse to the magnetic lines of force.

By reference to Fig. 3 it will be seen that the electrodes are in closeproximity to the chute and that the ends of the chute protect thebinding-posts M from arcing.

On the cover is a spring-clip Q, secured thereto by a screw and adaptedto engage with the pin Q on the pole-piece F' to hold the cover inplace. Beads a a are provided on 9o the under side of the cover toprevent it from slipping endwise on the box.

The arcing electrodes and binding-posts, which are most readily injured,are so arranged that they may readily be inspected or replaced, and ifthe insulation between the electrodes and the pole-pieces is destroyed anew cover can be substituted at small expense.

ln Fig. 4 l have shown a diagram of the cir- 10o cuit connections, inwhich l represents the circuit to be protected, and connected thereto isthe terminal L. Terminal D is in circuit with the graphite rods Bandalso with ground, and the coil of the blow-out magnet. is connected tosupport E and clamp II. IVhen a lightning discharge takes place, itpasses over the electrodes G G through the rods B to ground. At the sametime a certain amount of current from the line passes through the' coilI, the resistance being less than that of the rods between the clamp andsupport. The dynamo-current is prevented, except momentarily, fromfollowing' the lightning discharge by the non-inductive resistance ofthe rods B, and any arc formed between the electrodes is immediatelydisrupted by the blowout magnet.

I have shown the non-inductive resistance connected to the ground side;but itis within the scope of myinvention to reverse the connections landput it on the line side of the arrester.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is-

l. In a lightning-arrester, the combination of arcing electrodes, anon-inductive resistance in circuit with one of the electrodes, and ablow-out magnet having the ends of its coil or coils connected to thenon-inductive resistance at points between which there is a differencein potential due to the dynamo-cu rrent following a lightning discharge.

2. In a lightning-arrester, the combination of an inclosing box, a coverformed with an extension on its under side, binding-posts secured to theextension, arcing electrodes mounted in the binding-posts, and anopening or chute through which the vapor formed at the time a lightningdischarge takes place can pass to the outside of the box.

3. In a lightning-arrester, the combination of an inciosing box, anextension formed on the under side of the cover, binding-posts securedto the extension, arcing electrodes mounted in the binding-posts, achute formed in the cover and its extension coinlnunicating with theexternalair, and a blow-out magnet arranged to blow the are formed atthe electrodes outward through the chute.

4c. In a lightning-ariester, the combination of an inclosiilg box ofinsulating material, a cover therefor, provided with an extension on itsunder surface, binding-posts secured to the extension, arcing electrodesseparated byan air-space mounted in the binding-posts, springcontact-arms forming a part of the binding-posts, ground and lineterminals making electrical connection with the spring contact-arms, andmeans for securing the cover to the box.

5. In a lightning-arrcster, the combination of an inclosing box, a covertherefor provided with an extension on its underside, bindingpostssecured to the extension, contacts on the binding-posts engaging withlfixed contacts on the box, arcing electrodes, a nou-ind uetiveresistance, an opening in the box communicating with the outside, and aspringclip engaging with a iixed part of the box to hold the cover inplace.

G. As an article of manu facture, a cover for a lightning-arrester,provided with an extension on its under side in which is formed a chute,projections on the extension, an d sockets in which the binding-postsare mounted.

In witness whereof I have hereunto set my hand this 12th day of March,1897.

EDWARD M. IIEWLET' Witnesses:

B. B. HULL, M. II. EMERSON.

